1. Field of the Invention
The present invention relates to a signal transfer system, a signal outputting circuit board, a signal receiving circuit board, a signal outputting method and a signal receiving method. More specifically, the invention relates to a signal transfer system for transmitting a signal, a signal outputting circuit board and a signal outputting method for sending out a signal to the outside and a signal receiving circuit board and a signal receiving method for receiving a signal from the outside.
The present application relates to Japanese Patent Application No. 2005-004481 filed on Jan. 11, 2005. The contents described therein will be incorporated in the present application as part of description of the present application.
2. Related Art
A high-frequency signal attenuates largely as compared to a low-frequency signal depending on frequency characteristics of a transmission line in transmitting a high-speed signal by using the transmission line such as a cable and signal lines on a board in general. This is a big problem in a test apparatus and a measuring system of semiconductor devices. Then, conventionally, there has been used a method of reducing the difference of attenuation level of high and low-frequency signals by providing a peaking circuit that largely attenuates a low-frequency signal more than a high-frequency signal on a signal transmission line.
However, because impedance of the peaking circuit that is used to largely attenuate the low-frequency signal more than the high-frequency signal varies as frequency of a signal to be transmitted becomes high, it has been difficult to match the impedance in the transmission line.
A need for transmitting a high frequency signal is increasing lately in a signal transfer system of the test apparatus and measuring system of semiconductor devices. However, even though the difference of attenuation level of the high and low-frequency signals is reduced in the signal transfer system in which the peaking circuit is provided in its transmission line as described above, it is posing a big problem because the higher the frequency, the more remarkable the mismatch of impedance becomes, thus increasing a signal loss.